Work has begun on a Wi-Fi Display (WFD) specification providing connectivity schemes by which a WFD source device (e.g., a smartphone, laptop or other mobile device) can discover and communicate with a WFD sink device (e.g., digital televisions, monitors, set-top boxes, etc.) on which the WFD source device may wish to play audio and/or video content. In particular, WFD devices can communicate with each other using a direct, “peer-to-peer” (P2P) connection, or via an intermediary such as an access point (when in an IEEE 802.11 infrastructure mode) or P2P group owner. Communications via an access point or P2P group owner may use Tunneled Direct Link Setup (TDLS) connectivity, as defined in the IEEE 802.11z standard.
In addition to allowing P2P and TDLS connectivity for data communications, the current WFD specification allows a WFD device to discover other WFD devices in the vicinity using either a P2P discovery mechanism, in which probe request frames and probe response frames are exchanged directly between WFD devices, or a tunneled discovery mechanism, in which tunneled probe request frames and tunneled probe response frames are exchanged via an access point. The current WFD specification requires that devices support P2P discovery, with additional support for tunneled discovery being optional. The WFD specification also specifies the manner in which WFD devices should resolve the type of connectivity (P2P or TDLS) to be used for link establishment, with the connectivity type depending on the respective connectivity types preferred by the discovering device and the discovered device. Problems may arise, however, when discovery is conducted according to one type (TDLS or P2P), but the communication link is to be established according to the other type (P2P or TDLS). In particular, because a WFD device may use different interfaces (with different addresses) for P2P communications and TDLS communications, the current specification does not provide a reliable mechanism for utilizing discovery of one type and then establishing a link of the other type. Without such a mechanism, it may be impossible to maintain tunneled discovery as an optional feature in WFD devices.